I just finished breeding my two yorkies about 2 weeks ago. It was their first time and mine also (as far as being a part of the actual breeding process). I had a litter with a different female a couple of years ago, that time my female went to a stud for breeding.
Like you, our first attempts resulted in outside ties for what seemed like just seconds; certainly not 3-5 minutes like you described, so you've done better than me there. But starting on about day 12 or 13 it was a whole different story. My female was MUCH more receptive to my male (totally standing for him) and my male was even more eager & crazy in wanting my female than he was before! We had a total of 3 successful 5-10 minutes ties (no, not all in one day). I really think that she was not quite "ready" before those days, resulting in the outside ties. Maybe that is what's happening with your pair too.
Now the wait and see game begins. Ooooo, I hate this part! I drive myself (and my female probably) crazy checking her belly every day for any tiny change.
If I remember correctly from the pregnancy 2 years ago, I think I highly suspected that my girl was PG 3-4 weeks after the first tie. Her nipples were prominent and her belly felt a bit firmer. At about the time I was pretty sure, we were able to take her in for palpitation and the vet confirmed the pregnancy.
GOOD LUCK TO YOU!